watchOS 5.3 (build 16U6569) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2019-07-22T19:17:25Z. The update package is 142.6 MB. This is a delta (partial) update that requires 5.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: e76620a876a72caa422608462c4a5183b77d2b8c.zip.